N1-(5-chloropyridin-2-yl)-N2-((1S, 2R, 4S)-4-[(dimethylamino)carbonyl]-2-{[(5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridin-2-yl)carbonyl]amino}cyclohexyl)ethanediamide p-toluenesulfonate monohydrate represented by the following formula (I) (in the present specification, also referred to as compound I):
is known as a compound that exhibits an inhibitory effect on activated blood coagulation factor X (FXa) and is useful as a preventive and/or therapeutic drug for thrombotic diseases (Patent Documents 1 to 9). Crystals described in Patent Document 9 (in the present specification, also referred to as “Form I crystals of compound I” or “Form I crystals”) are known as crystals of compound I.